VRIJE UNIVERSITEIT BRUSSEL Acoustics - the Dept. of ...

132 CHAPTER 8. NOISE ON THE WORK FLOORIf risks arising from the exposure to noise cannot be prevented in anyother way, appropriate, properly fitting individual hearing protection mustbe made available to the employees :When the lower action value is exceeded, hearing protection is madeavailable for the employees.When the upper action value is exceeded, hearing protection must beused.The individual hearing protection is selected in such a way that the risk onhearing impairment is eliminated or limited to a minimum (see further). Theemployer is responsible for the application of the actions taken in this articleand takes care that the employees wear the hearing protection.The employees thatexecute anactivity witharisk duetonoise, where theexposure exceeds the lower action value, are subject to prior health examination(an examination of the hearing by means of a pre-emptive audiometricexamination, see further). The periodicity of the health examination is determinedas follows :Yearly for employees who are exposed to a daily average exposureequal or larger to 87 dB(A) or a peak sound pressure of 140 dBC;Once every three years for employees who are exposed to an averagedaily exposure equal to or larger than 85 dB(A) or a peak soundpressure of 137 dBC;Once every five years for employees who are exposed to an averagedaily exposure equal or larger than 80 dB(A) or a peak sound pressureof 135 dBC.8.3 Risk of hearing damageOccupational deafness is permanent and irreversible hearing loss, caused byordinary working conditions. Certain types of occupational deafness maybe due to toxic products such as carbon monoxide (CO), carbon disulfide,benzene and lead. Others are due to brief exposure to intense sounds (e.g.gunshots or explosions), wherein a rupture occurs of the basilar membranein the cochlea of the eardrum, or, in the case of an explosion, the ossicles areaffected.